Oil-gas separated pressure cylinder

ABSTRACT

An oil-gas separated pressure cylinder, which combines a hydraulic cylinder, a pneumatic cylinder and a pres-pressure cylinder, and keeps the applied compressed gas and the storage hydraulic fluid apart, maintaining the quality of the hydraulic fluid and saving the hydraulic fluid replacement cost. When the applied compressed gas enters the pre-pressure cylinder to move a pre-pressure cylinder piston in forcing the storage hydraulic fluid out of an oil storage space of the pre-pressure cylinder into an oil storage space in the hydraulic cylinder, a hydraulic cylinder piston of the hydraulic cylinder is then forced by the hydraulic fluid to move a hydraulic cylinder piston rod against the workpiece, and then a pneumatic cylinder piston rod of the pneumatic cylinder is forced into the oil storage space of the hydraulic cylinder to enhance the pressure at the hydraulic cylinder piston rod against the workpiece.

BACKGROUND OF THE INVENTION

1. Field of the Invention

The present invention relates to a pressure cylinder and moreparticularly, to an oil-gas separated pressure cylinder.

2. Description of the Related Art

Referring to FIG. 1, a conventional pressure cylinder 10 generallycomprises a hydraulic cylinder 12, an air cylinder 14 verticallyconnected to the hydraulic cylinder 12, and a pre-pressure cylinder 16laterally connected to the hydraulic cylinder 12. As illustrated in FIG.2, when a compressed gas from an external pressure source enters an oilstorage chamber 162 of the pre-pressure cylinder 16, the hydraulic fluidin the oil storage chamber 162 of the pre-pressure cylinder 16 will beforced through an oil passageway 18 into an oil storage chamber 122 ofthe hydraulic cylinder 12 to convert the received gas pressure to apre-pressure against a piston 124 of the hydraulic cylinder 12. At thistime, the piston rod 126 of the hydraulic cylinder 12 will be movedgradually toward the workpiece. Thereafter, the piston rod 142 of theair cylinder 14 will be forced by the air pressure generated by the aircylinder 14 to enter the oil storage chamber 122 of the hydrauliccylinder 12, enhancing the pressure at the piston rod 126 of thehydraulic cylinder 12 against the workpiece.

However, during the operation of the aforesaid prior art pressurecylinder 10, the hydraulic fluid in the pre-pressure cylinder 16 isinevitably kept in contact with the inputted compressed gas. If theinputted compressed gas contains a high percentage of water, thehydraulic fluid may be emulsified. Quality deterioration of thehydraulic fluid will affect the performance and lifespan of the internalcomponents of the pressure cylinder. To avoid this problem, the operatormust regularly replace the hydraulic fluid. However, regularly replacingthe hydraulic fluid greatly increases the material cost. Further, afterthe working stroke of the pressure cylinder 10, the return pressure ofthe hydraulic fluid of the pre-pressure cylinder 16 forces the inputtedcompressed gas toward the outside. However, the fluid mixture of thehydraulic fluid and the compressed gas may be volatized into the outsideopen air during compressed gas discharging process, causing airpollution and bringing harm to the health of the operator. Further, inorder to facilitate movement of the hydraulic fluid by the pressure ofthe inputted compressed air, the pressure cylinder 10 can simply be setin vertical, limiting its application.

Therefore, there is a room for improvement on the conventional pressurecylinder.

SUMMARY OF THE INVENTION

The present invention has been accomplished under the circumstances inview. It is the main object of the present invention to provide anoil-gas separated pressure cylinder, which has less limitation ininstallation, maintains the quality of the hydraulic fluid, saves thehydraulic fluid replacement cost, and reduces air pollution.

To achieve this and other objects of the present invention, an oil-gasseparated pressure cylinder comprises a hydraulic cylinder, a pneumaticcylinder, and a pre-pressure cylinder. The hydraulic cylinder comprisesa first oil storage space, a hydraulic cylinder piston set in the firstoil storage space and a hydraulic cylinder piston rod connected to thehydraulic cylinder piston. The pneumatic cylinder is connected to oneend of the hydraulic cylinder, comprising a pneumatic cylinder pistonand a pneumatic cylinder piston rod. The pneumatic cylinder piston rodhas one end thereof connected to and movable by the pneumatic piston,and an opposite end thereof inserted into the first oil storage space ofthe hydraulic cylinder The pre-pressure cylinder is connected to oneside of the hydraulic cylinder, comprising a second oil storage space incommunication with the first oil storage space, a gas passage incommunication with the second oil storage space and a pre-pressurecylinder piston set in the second oil storage space within an output endof the gas passage and movable by an applied compressed gas.

Based on the aforesaid design, the air-gas separated pressure cylindercan be set in any desired direction. Further, the gas passage forcompressed gas is isolated from the second oil storage space forhydraulic fluid by the pre-pressure cylinder piston of the pre-pressurecylinder, avoiding contact between the compressed gas and the hydraulicfluid. Thus, the quality of the hydraulic fluid is maintained, reducingthe number of hydraulic fluid replacement times, saving the hydraulicfluid replacement cost and avoiding production of hydraulic fluid-gasmixture that may pollute the air.

Other advantages and features of the present invention will be fullyunderstood by reference to the following specification in conjunctionwith the accompanying drawings, in which like reference signs denotelike components of structure.

BRIEF DESCRIPTION OF THE DRAWINGS

FIG. 1 is a schematic sectional view of a pressure cylinder according tothe prior art.

FIG. 2 is a sectional view of an oil-gas separated pressure cylinder inaccordance with the present invention.

FIG. 3 illustrates an operation flow of the present invention.

DETAILED DESCRIPTION OF THE INVENTION

Referring to FIG. 2, an air-gas separated pressure cylinder 20 inaccordance with the present invention is shown. The air-gas separatedpressure cylinder 20 comprises a hydraulic cylinder 30, an air cylinder40, and a pre-pressure cylinder 50.

The hydraulic cylinder 30 comprises a hydraulic cylinder body 31, ahydraulic cylinder piston 32, a hydraulic cylinder piston rod 33, a sealmember 34, and a spacer 35. The hydraulic cylinder piston 32 is set inthe hydraulic cylinder body 31 and movable by the pressure of ahydraulic fluid. The hydraulic cylinder piston rod 33 has its top endconnected with the hydraulic cylinder piston 32 and its bottom endfacing toward the workpiece 60, and is movable by the hydraulic cylinderpiston 32 to force its bottom end against the workpiece 60. The sealmember 34 is mounted at the top end of the hydraulic cylinder body 31,defining with the hydraulic cylinder piston 32 a first oil storage space36 for storing a hydraulic fluid 70. The spacer 35 is set between theseal member 34 and the hydraulic cylinder piston 32 to divide the firstoil storage space 36 into an oil storage chamber 362 and a pressurechamber 364, wherein the volume of the pressure chamber 364 varies withthe position of the hydraulic cylinder piston 32. Further, the hydrauliccylinder body 31 defines a radially extending first oil guide passage 37in communication with the oil storage chamber 362 of the first oilstorage space 36.

The air cylinder 40 comprises a pneumatic cylinder body 41, a pneumaticcylinder piston 42, and a pneumatic cylinder piston rod 43. Thepneumatic cylinder body 41 has its bottom end connected to the top endof the hydraulic cylinder body 31 of the hydraulic cylinder 30. Thepneumatic cylinder piston 42 is set in the pneumatic cylinder body 41and movable by a compressed gas. The pneumatic cylinder piston rod 43has its top end connected to the pneumatic cylinder piston 42 and itsbottom end inserted through the seal member 34 into the inside of theoil storage chamber 362 of the hydraulic cylinder 30, and is movable bythe hydraulic cylinder piston 42 to force its bottom end into thepressure chamber 364 of the hydraulic cylinder 30, as shown in FIG. 3,thereby enhancing the pressure.

The pre-pressure cylinder 50 comprises a pre-pressure cylinder body 51,a pre-pressure cylinder piston 52, and an oil filing tube 53. Thepre-pressure cylinder body 51 is connected to one side of the hydrauliccylinder 30, comprising a second oil storage space 54 and a radiallyextending oil guide passage 55 in communication with the second oilstorage space 54 and the first oil guide passage 34 of the hydrauliccylinder 30. The pre-pressure cylinder body 51 further comprises a gaspassage 56 in communication with the second oil storage space 54 foraccess of an external compressed gas. The pre-pressure cylinder piston52 is set in the second oil storage space 54 within the output end ofthe gas passage 56, and movable toward the bottom side by the pressureof the applied compressed gas. The oil filing tube 53 has its bottom endconnected to the pre-pressure cylinder piston 52, and its top endextending out of the pre-pressure cylinder 50 and terminating in an oilfilling hole 532 for allowing the operator to fill a new supply ofhydraulic fluid 70 into the second oil storage space 54 as well as forexhausting air.

After understanding of the structural details of the oil-gas separatedpressure cylinder 20, the operation and features of the oil-gasseparated pressure cylinder 20 are outlined hereinafter.

Referring to FIG. 3 and FIG. 2 again, a compressed gas is guided from anexternal pressure source through the gas passage 56 of the pre-pressurecylinder 50 into the second oil storage space 54 to force thepre-pressure cylinder piston 52 of the pre-pressure cylinder 50 throughthe second oil guide passage 55 and the first oil guide passage 37 inforcing the hydraulic fluid 70 from the second oil storage space 54 intothe first oil storage space 36 of the hydraulic cylinder 30. At thistime, the hydraulic fluid 70 gives a pre-pressure to the hydrauliccylinder piston 32 of the hydraulic cylinder 30, forcing the hydrauliccylinder piston 32 of the hydraulic cylinder 30 to move the hydrauliccylinder piston rod 33 toward the workpiece 60. When the hydrauliccylinder piston rod 33 is approaching the workpiece 60, the pneumaticcylinder piston rod 43 of the pneumatic cylinder 40 is forced by the gaspressure of the pneumatic cylinder 40 to enter the pressure chamber 364of the hydraulic cylinder 30, enhancing the pressure at the hydrauliccylinder piston rod 33 against the workpiece 60. After working at theworkpiece 60, the hydraulic cylinder 30, the pneumatic cylinder 40 andthe pre-pressure cylinder 50 are returned to their respective formerpositions for a next processing cycle.

Based on the aforesaid design, the air-gas separated pressure cylinder20 can be set in vertical, horizontal or any other direction withoutaffecting the operation of the pre-pressure cylinder piston 52 in movingthe hydraulic fluid 70. Thus, the invention facilitates the installationof the air-gas separated pressure cylinder 20. Further, the gas passage56 for compressed gas is isolated from the second oil storage space 54for hydraulic fluid 70 by the pre-pressure cylinder piston 52 of thepre-pressure cylinder 50, avoiding contact between the compressed gasand the hydraulic fluid 70 either in the pre-pressure stroke, pressurestroke or return stroke Thus, the quality of the hydraulic fluid 70 ismaintained, reducing the number of hydraulic fluid replacement times,saving the hydraulic fluid replacement cost and avoiding production ofhydraulic fluid-gas mixture that may pollute the air.

Although a particular embodiment of the invention has been described indetail for purposes of illustration, various modifications andenhancements may be made without departing from the spirit and scope ofthe invention. Accordingly, the invention is not to be limited except asby the appended claims.

1. An oil-gas separated pressure cylinder, comprising: a hydrauliccylinder comprising a first oil storage space, a hydraulic cylinderpiston set in said first oil storage space and a hydraulic cylinderpiston rod connected to said hydraulic cylinder piston; a pneumaticcylinder connected to one end of said hydraulic cylinder, said pneumaticcylinder comprising a pneumatic cylinder piston and a pneumatic cylinderpiston rod, said pneumatic cylinder piston rod having one end thereofconnected to and movable by said pneumatic piston and an opposite endthereof inserted into said first oil storage space of said hydrauliccylinder; and a pre-pressure cylinder connected to one side of saidhydraulic cylinder, said pre-pressure cylinder comprising a second oilstorage space in communication with said first oil storage space, a gaspassage in communication with said second oil storage space and apre-pressure cylinder piston set in said second oil storage space withinan output end of said gas passage.
 2. The oil-gas separated pressurecylinder as claimed in claim 1, wherein said hydraulic cylinder furthercomprises a seal member and a spacer, said seal member defining withsaid hydraulic cylinder piston said first oil storage space, said spacerbeing set between said seal member and said hydraulic cylinder piston todivide said first oil storage space into an oil storage chamber and apressure chamber, said oil storage chamber being in communication withsaid second oil storage space of said pre-pressure cylinder, saidpressure chamber having a volume variable with the position of saidpneumatic cylinder piston; said pneumatic cylinder piston rod of saidpneumatic cylinder is inserted through said seal member into said oilstorage chamber and forcible by said pneumatic cylinder piston into saidpressure chamber.
 3. The oil-gas separated pressure cylinder as claimedin claim 1, wherein said hydraulic cylinder further comprises a firstoil guide passage in communication with said first oil storage space;said pre-pressure cylinder further comprises a second oil guide passagein communication with said second oil storage space and said first oilguide passage.
 4. The oil-gas separated pressure cylinder as claimed inclaim 1, wherein said pre-pressure cylinder further comprises an oilfilling tube, said oil filling tube having one end thereof connected tosaid pre-pressure cylinder piston and an opposite end thereof extendingout of said pre-pressure cylinder and terminating in an oil fillinghole.
 5. The oil-gas separated pressure cylinder as claimed in claim 2,wherein said hydraulic cylinder further comprises a first oil guidepassage in communication with said first oil storage space; saidpre-pressure cylinder further comprises a second oil guide passage incommunication with said second oil storage space and said first oilguide passage.